Evaluation of vertical facial height reduction and severity of temporomandibular joint disorders using Shimbashi number and cephalometric analysis.

Objective: This study was designed to evaluate the correlation between vertical dimension at occlusion (VDO) and various grades of temporomandibular disorders (TMDs) versus controls.Methods: Clinically measured Shimbashi number and radiographic cemento-enamel junction (CEJ-CEJ) measurements on 120 TMD patients and 40 controls were evaluated. Radiographic lateral cephalometric skull images of the patients were subjected to cephalometric analysis. The relationship between Shimbashi number, the cephalometric values, and its correlation with the degree of TMD were evaluated and statistically analyzed.Results: Shimbashi number and radiographic CEJ-CEJ values in the TMD patients were significantly lower than those in the controls. TMD severity appeared to increase with the increase in interincisal angle and the decrease in both Shimbashi number and radiographic CEJ-CEJ value.Conclusion: These findings indicate that radiographic evaluation of cephalograms is a reliable indicator of presence and degree of TMD, and the severity of TMD increases with the degree of reduction in VDO.